1. Field of the Disclosure
The present disclosure relates generally to a lubricant dispenser for a fuser assembly in an electrophotographic imaging device, such as a laser printer or multifunction device having printing capability.
2. Description of the Related Art
An image forming machine, such as a printer, copier, all-in-one device or multifunctional device, typically includes a heating device, such as a fuser, to fix a developing agent, such as toner, to a media sheet. The fuser typically contains a heater and an endless belt and backup pressure roll that form a nip for the media sheet to pass through. The heater and belt provide heat and/or pressure to the toner to soften the toner so that it will adhere to the media sheet. The fuser belt defines an inner loop. The heater is positioned within the inner loop in direct contact with the belt. The heater has a profile generally corresponding to the travel path of the belt to provide an area contact rather than a line contact for more efficient thermal transfer. The heater is typically in the form of a ceramic heater held in a heater housing positioned within the inner loop and against the belt. The fuser belt is an “idling belt” having no drive roils within it. The belt is driven by the rotation of the backup pressure roll, through the driving association of the belt with the pressure roll at the nip.
An issue with today's fusers is that only a portion of the lubricant that is applied to the fuser components during manufacture is available over the life of the fuser for reducing the friction between the belt and the heater. Only a certain amount of lubricant can be kept in the system and any excess lubricant will be pushed out of the belt at the very early stages of fuser life. As the lubricant is contaminated or broken down chemically and mechanically, the friction between the belt and the heater increases, belt wear increases, thereby leading to even more friction and more wear, until the frictional forces between the paper and the belt are insufficient to drive the belt. When the paper can no longer drive the belt, a paper jam occurs.
At a top level view, the lubricant can be viewed as two separate parts: 1) filler, and 2) oil. The filler makes up the majority of the total initial lubrication applied during assembly (at least 80%) and is designed to retain the oil.
Small amounts of oil reduce and maintain a desired fuser drive torque over a specified timeframe. Over time, the oil is removed from the filler via evaporation and/or run-off and new oil is required to reduce and maintain low fuser drive torque. Testing has indicated that additional oil introduced to the belt assembly every predetermined number of pages, such as 50,000 pages, serves to maintain a desired fuser drive torque.